(a) Field of the Invention
The present invention relates to a GGSN (gateway GPRS supporting node) in a GPRS (general packet radio service) system. More specifically, the present invention relates to a GPRS system having multiple GGSNs and a method for selecting a GGSN for increasing system capability through distribution and enabling fluent management according to traffic variation.
(b) Description of the Related Art
A GPRS system is a packet-based radio communication service, which became available in 2000, guaranteeing mobile phone and computer users access to the Internet without interruption at the 56 through 114 Kbps data speeds.
Because of fast data transmission by the GPRS system, the users may take part in video conferences, and use a mobile device as well as a notebook computer to perform interactive communication with multimedia web sites.
The GGSN links an inner GPRS network of the GPRS system to a public network. All the packets transmitted by a mobile station are provided to the public network through the GGSN, and all the packets on the public network are transmitted to the mobile station through the GGSN.
Therefore, the GGSN functions as a gateway for performing routing between the inner network and the public network.
FIG. 1 shows a block diagram of a general GPRS system.
Referring to FIG. 1, the GPRS system comprises an SGSN (serving GPRS supporting node) 101, a GPRS network 102, a GGSN 103, an operator network 104, an FA (foreign agent) 105, a DNS (domain name system) 106, a DHCP (dynamic host configuration protocol) 107, an edge router 108, and a public network 109.
The SGSN 101 is session-connected to the GGSN 103 selected in response to a session request by a terminal so as to perform packet transmission in the connected session state.
The operator network 104 is provided between the GGSN 103 and the public network 104 so as to perform communication with subsidiary devices including the DNS, the DHCP 107, and the FA 105 in addition to the GGSN 103.
Also, the edge router 108 adjacent to the public network 109 is a final end of the GPRS system, it operates a routing protocol including the RIP (routing information protocol) and the BGP (border gateway protocol), and performs a security function in the like manner of a firewall or the IPSEC (Internet protocol security protocol.)
The next two points regarding the GGSN 103 in the GPRS system as shown in FIG. 1 need to be considered.
First, the GGSN 103 functions as a gateway between the public network 109 and the GPRS network 102. When a problem occurs in the GGSN, the GPRS system no longer provides any service, and in particular, users who employ static IPs (Internet protocols) cannot set sessions.
To solve the above-noted problem, the GGSN 103 is realized as fault-tolerant hardware and software, and a method for using both hardware and software is sometimes used. However, this method increases the cost of building GGSNs with respect to the standby mode, and wastes resources since the GGSN does not have a processing function in the standby mode.
Second, the GGSN 103 may also function as a packet router because it is a final end of GTP (GPRS tunneling protocol) messages tunneled by the GTP.
Therefore, general packets transmitted and received by application programs of a mobile station are provided within the GGSN 103, and the general packets are routed by an IP layer. Hence, the GGSN 103 has a performance problem that commercial routers on the Internet have.
To solve the problem, an efficient hardware and software structure is required so as to process traffic reached by the GGSN 103 without delays.
However, the traffic required from the GGSN 103 is not determined at the instant of arrangement, and the required traffic may be increased or decreased depending on the number of users on the public network 109. Therefore, the GGSN 103 needs flexible processing performance in preparation for traffic increase and decrease.